a music cooperative specialising in contemporary music performance, improvisation, and artistic education, founded in 2013 by utist Ania Karpowicz. The group brings together 20 outstanding Polish musicians. 

The group’s activity is based on programmes built around extramusical context. An important element of their concert practice is supporting and presenting the artistic achievements of women, as expressed through their ongoing cooperation with female composers and artists. Concerts in the courtyards of Warsaw townhouses (within the WarszeMuzik festival) and on the city’s streets testify to Hashtag Ensemble’s rooting in and integration with the local community. 

The ensemble has been invited by many national and international festivals and musical institutions such as Warsaw Autumn, Sacrum Profanum, Intersonanzen, Sinfonia Varsovia, POLIN Music Festival, Tallinn/Tartu, Afekt Festival, Poznań Music Spring, Musica Electronica Nova, Musical Gardens, and Warsaw Music Meetings. 

The Hashtag Ensemble is also engaged in promoting the music of young composers, including prizewinners at the Tadeusz Baird Young Composers Competition, Zygmunt Mycielski Composition Competition, and Kazimierz Serocki International Composition Competition. 

Another important aspect of their activity is improvisation, expressed in four threads:
#archi-solos: musical interpretations of Cracow’s architecture; urb<s>core, closed improvisation forms based on urbanistic photographic scores; 

#WITKACY (Requiem Records, Opus Series, 2018): musical readings of the photographic autoportraits of Stanisław Ignacy Witkiewicz;


Visegrad Songs (Requiem Records, Opus Series, 2016): reinterpretations of motifs borrowed from 19th-century classical music. The Hashtag Ensemble’s repertoire CDs include Openings of the (eye) (Bôłt Records 2020), the first monographic recording of composer Lucia Dlugoszewski; First Command (DUX 2019), Adam Porębski’s electroacoustic suite after the prose of Joseph Conrad; Trash Music (Requiem Records, Opus Series, 2018), a study of Wojciech Błażejczyk’s art; and #NetworkMusic, a record of the ensemble’s research and development in the years 2013–17. The Hashtag Ensemble is also involved in artistic education. In the years 2016–18, they have presented a regular cycle of educational contemporary music concerts at the Ujazdowski Castle Centre for Contemporary Art in Warsaw (part of the Smykowizje project). In 2017 alone, they have played 34 concerts for over 1,000 families, presenting the works notably of Crumb, Andriessen, Schoenberg, and Penderecki as well as many young Polish composers. The Hashtag Ensemble also runs masterclasses for composers (notably in cooperation with the CEME Festival in Israel, 2020) and performers (Afekt Festival, Tartu/Tallinn 2018).
 The Hashtag Ensemble initiates and moderates partnerships with new music ensembles in Poland and in Europe (Riot Ensemble, Meitar Ensemble, NeoQuartet, Spółdzielnia Muzyczna), supporting a deepening of relations with the contemporary music milieu, both musical and institutional.